Large inverted band-gap in strained three-layer InAs/GaInSb quantum wells

TL;DR

This paper reports the achievement of a large, temperature-independent inverted band-gap of up to 45 meV in strained three-layer InAs/GaInSb quantum wells, enabling robust topological edge transport at higher temperatures.

Contribution

The study demonstrates a significantly larger and temperature-stable band-gap in InAs/GaInSb quantum wells, advancing the potential for high-temperature topological insulator applications.

Findings

Achieved a 45 meV inverted band-gap in strained three-layer InAs/GaInSb QWs.

Observed topological edge channels with short equilibration lengths up to 40 K.

Established temperature-independent edge conductivity up to 40 K.

Abstract

Quantum spin Hall insulators (QSHIs) based on HgTe and three-layer InAs/GaSb quantum wells (QWs) have comparable bulk band-gaps of about 10--18~meV. The former however features a band-gap vanishing with temperature, while the gap in InAs/GaSb QSHIs is rather temperature-independent.Here, we report on the realization of large inverted band-gap in strained three-layer InAs/GaInSb QWs. By temperature-dependent magnetotransport measurements of gated Hall bar devices, we extract a gap as high as 45 meV. Combining local and non-local measurements, we attribute the edge conductivity observed at temperatures up to 40 K to the topological edge channels with equilibration lengths of a few micrometers. Our findings pave the way toward manipulating edge transport at high temperatures in QW heterostructures.